Ribbon-lifting mechanism for a typewriter

ABSTRACT

A ribbon-lifting mechanism for a typewriter comprising a toggle mechanism the common ends of whose links are pivotally mounted on a drive arm, the other end of one link is fulcrumed on a bistable shiftable support, and the other end of the other link is pivotally connected to a ribbon lift crank. The drive arm is operable on each forward stroke to open or straighten and on each rearward stroke to close or break the toggle about its fulcrum. A bistable trip lever also pivotally mounted on the drive arm is conditioned on each forward stroke of the drive arm to shift the position of the bistable support on each rearward stroke of the drive arm, and as a result of the shifting movement of the bistable support a ribbon vibrator connected to the toggle mechanism is elevated alternately through full and partial strokes on succeeding forward strokes of the drive arm whereby in combination with ribbon movement a zigzag pattern is defined on a carbon ribbon to utilize the maximum area of the carbon ribbon.

United States Patent 3,171,530 3/1965 ODanieletal............... 197/1513,348,650 10/1967 Meinherz etal. 197/158 X Primary Examiner- Robert E.Pulfrey [72] inventor Robert E. McGrath Rocky Hill. Conn. 808,570

[21] Appl. No.

gg s 10 I971 Assistant Examiner-Stephen C. Pellegrlno Assign um)Business sysems hm AltomeysJ0seph R. Spalla and Cornelius P. Quinn NewYork, N.Y.

ABSTRACT: A ribbon-lifting mechanism for a typewriter comprising atoggle mechanism the common ends of whose links are pivotally mounted ona drive arm. the other end of one link is fulcrumed on a bistableshiftable support. and the other end of the other link is pivotallyconnected to a ribbon lift crank. The drive arm is operable on eachforward stroke to open or straighten and on each rearward stroke toclose or l A R m m M B m N n m M C 5M E m M 8 G u m m m em NW mnm wYCsRT6U H H U [51]Int.Cl...............r...................................1.....B4lj35/22.

break the toggle about its fulcrum. A bistable trip lever also pivotallymounted on the drive arm is conditioned on each for- Fie 01 ward strokeof the drive arm to shift the position of the bistable support on eachrearward stroke of the drive arm, and as a result of the shiftingmovement of the bistable su pport a rib- [56] References Cited UNITEDSTATES PATENTS bon vibrator connected to the toggle mechanism iselevated alternately through full and partial strokes on succeedingforward strokes of the drive arm whereby in combination with ribbonmovement a zigzag pattern is defined on a carbon ribbon to utilize themaximum area of the carbon ribbon.

3,139,964 7/1964 Fischer........................ 197/157 3.154.18510/1964 l97/156X PATENTEDAUBIOISYI 9,598,220

sum 1 0r 6 STENCIL CARBON INVENTOR ROBERTE.McGRATH BY M ATT RNEYPATENTED AUG] 0 IBYI I sum 2 UF 6 INVENTOR ROBERT E. McGRATH KLQMQ a? 14AT ORNEY PATENTEUAUBIOIQH $3,598,220

sum 3 or 6 INVENTQR ROBERT E. McGRATH ATTO NEY PATENIEU AUG] 0 mm SHEET0F 6 INVENTOR ROBERT E. McGRATH ATTO NEY .ESQHZZO PATENTED AUG] 0 ISYISHEET 5 0F 6 INVENTOR ROBERT E. MCGRATH yin M44.

ATTO NEY PATENTED AUG 1 0 I971 SHEET 8 BF 6 INVENTOR McGRATH ATT RNEYROBERT E.

BY (TQM DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention isparticularly directed to a carbon ribbon vibrator for use in atypewriter having the capability of switching between, a fabric ribbonoperational mode, a carbon ribbon operational mode and a stenciloperational mode, in accordance with the typewriter ribbon selectorcontrol apparatus described and claimed in copending U.S. Pat.application Ser. No. 808,516, of Ronald H. McLean filed concurrently onMar. 19, 1969.

Referring now to the drawing wherein like reference characters designatelike or corresponding parts throughout the several views, there isillustrated in FIG. 1 a type action, generally designated by thereference numeral 10, operable to power a U-bar 11 adapted toselectively drive appropriate ribbon vibrator assemblies for elevating afabric ribbon vibrator, generally designated by the reference numeral12, supporting a fabric ribbon FR and a carbon ribbon vibrator,generally designated by the reference numeral 13, supporting a carbonribbon CR.

As illustrated in FIG. 1, the U-bar 11 moves counterclockwise about across-shaft 14 as will hereinafter appear, in response to type actionoperation initiated by the depression of alphanumeric key levers such asa key lever 15. The key lever 15 is fulcrumed on a cross-shaft 16secured to the typewriter frame and is formed with a depending finger 17engaging the upper surface of a bent off shelf 18 formed on the forwardend of a rigid or nonflexible intermediate control lever 19 pivotallymounted on a cross-shaft 20. An angularly extending rearward portion oflever 19 terminates with a tip 21 that normally underlies the lower edgeof a tail 22 formed on a rockable cam 23. The cam 23 is pivotallymounted on a sublever 24 of an actuating linkage, generally identifiedby the reference numeral 25, pivotally mounted on the cross-shaft 14,and is biased in a counterclockwise direction by a spring 26. Thecounterclockwise limit of movement of the cam 23 relative to thesublever 24 is determined by the engagement of a bent-off ear 23a on thecam 23 with an adjacent edge 24a of sublever 24. The actuating linkage25 is articulately connected by a link 27 to a type bar 28 pivotallymounted on a segment wire 29 and is adapted to drive the type bar 28from a normal position on a headrest 30 into printing contact with atypewriter platen 31, and at the same time, through a tail 32, extendingfrom the sublever 24 and overlying the U-bar 11, move the U-bar 11counterclockwise.

In operation, the rockable cam 23 is displaced in a clockwise directionin response to the depression of the key lever.l5 so as to move intofrictional driving engagement with a constantly rotating power roll 33,thereby initiating a powered printing stroke to the type bar 28 andcounterclockwise movement of the U-bar 11. After typing impact, the typebar 28 and the sublever 24 are returned to their normal positions bymeans of a return spring 34, allowing the U-bar 11 to return to a normalclockwise position through the action of a biasing spring (not shown).

The fabric ribbon vibrator l2 and the carbon ribbon vibrator 13 are bothpositioned behind a type guide generally designated by the referencenumeral which is fastened to a shiftable type bar segment 36 by a pairof screws 350. The fabric ribbon vibrator 12 has a pair of bent overears 12a and 12b in slidable engagement with the spaced vertical legs35a and 35b of the type guide 35 and has a depending leg 121' whoselower end is rockably mounted on a stud 37 formed on a lever 38 rigidlymounted on a shaft 39.

The carbon ribbon vibrator 13 has a leg 40 whose upper end is bent andbifurcated forming a slot 40a by which it has guided association withthe side edges of the upper portion of the fabric ribbon vibrator leg12c, and whose lower end is formed in a generally inverted U-shape withits ends rockably mounted on studs 41 formed on a pair of levers 42rigidly mounted on a vibrator elevating rod 43. Tension in the carbonribbon, applied by a carbon ribbon drive mechanism (not shown), avoidsforward and rearward movement of the carbon ribbon vibrator 13.

As illustrated in FIG. 2, a carbon ribbon vibrator drive assembly,generally designated by the reference numeral 44, is adapted to drivethe carbon ribbon vibrator elevating rod 43, in response tocounterclockwise movement of the U-bar 11 occasioned by a type actionwhen a ribbon control selector dial 45, shown in FIG. 3 and manuallyrotatable about a crossshaft 46, is set to a carbon ribbon operationalmode.

The carbon ribbon vibrator drive assembly 44 includes a drive link 47having an elongated slot 48 in its forward end with an upwardlyextending notch 480 formed in the rear of the elongated slot 48. A drivepin 49 extending laterally outward from an upwardly extending arm 11a ofthe U-bar l 1 and into the elongated slot 48, is received in the notch48a when the drive arm 47 is held downwardly by a biasing spring 50connected between the drive arm 47 and a frame mounted stud 50a. Withthe drive pin 49 in the detent 480, any counterclockwise movement of theU-bar 11 about the cross-shaft 14 will drive the drive arm 47 forward.

The detent 48a in the slotted end of the drive arm 47 is adapted to belifted out of driving engagement with the drive pin 49 by a bellcrank,generally designated by the reference numeral 51, pivotally mounted on aframe-mounted stud 52. The bellcrank 51 has a depending cam follower arm53 with an enlarged end portion 53a adapted to follow the surface of acam 54 formed on the ribbon selector control dial 45 (shown in FIG. 3),as the ribbon selector control dial 45 is moved between settings, andanother arm 55 with an enlarged end portion 55a underlying a laterallybent-out ear 56 on the bottom of the forward end of the drive arm 47.When the ribbon selector control dial 45 is moved from a carbon ribbonoperational mode, the cam 54 pivots the bellcrank 51 counterclockwise,as viewed in FIG. 2, raising the slotted end of the drive arm 47 and thedetent 48a so that the drive pin 49 is free to reciprocate in theelongated slot 48.

As illustrated in FIG. 2, in addition to extending into the elongatedslot 48 of the drive link 47 of the carbon ribbon vibrator assembly 44,the drive pin 49 also extends laterally from the extension Ila of theU-bar 11 into an elongated slot 48(/) formed in the forward portion of adrive link 470) of a fabric ribbon vibrator drive assembly (theremaining portion of which is not shown). An enlarged end portion 55amon an arm 55(/) ofa bellcrank (not shown) underlies a laterally bent outear 560) on the bottom of the forward end of the drive arm 47()) toraise and lower the slot 48(1) in relation to the drive pin 49 in orderthat the drive pin 49 is selectively free to reciprocate in the slot48(f). A complete description of the operation of the ribbon controlselector mechanism and the fabric ribbon vibrator drive assembly is setforth in the hereinabove-mentioned concurrently filed copending patentapplication of Ronald H. McLean.

During counterclockwise motion of the U-bar 11, the drive arm 47 isadapted to move forward (as shown by an arrow labeled A in FIG. 2) underthe action of the drive pin 49 and return under the action of the spring50 when the U-bar 11 returns to its normal position thereby driving atoggle assembly, generally designated by reference numeral 57, mountedon the drive link to rock the vibrator elevating rod 43 supporting thecarbon ribbon vibrator 13.

The toggle assembly 57 of the carbon ribbon vibrator drive assembly 44shown in FIG. 2, and as more clearly illustrated in FIG. 4, comprisestwo links 58 and 59 pivotally jointed together by a stud 60 fixed to thedrive link 47. The other end of the toggle link 59 is pivotally carriedon a bistable shifting plate or support 62 by a pivot stud 61 for givingthe lower end ofthe link 59 of the toggle assembly 57 one or anothersupport location. The other end of toggle link 58, is pivotallyconnected to a ribbon lift crank in the form on an arm 63 fixed to andextending outwardly from the vibrator elevating rod 43.

As best viewed in FIG. 5, the shifting plate or support 62 is pivotallymounted on a stud 66 on a frame bracket 64 mounted on a typewriter framemember 65. The shifting support plate 62 is adapted to shift the end ofthe toggle link 59 pivoted on the pivot stud 61 back and forth betweenan upper limit stop 67 and a lower limit stop 68, both of which limitstop RIBBON-LIFTING MECHANISM FOR A TYPEWRITER BACKGROUND OF THEINVENTION This invention relates to a typewriter having the capabilityof switching between a fabric ribbon operational mode, a carbon ribbonoperational mode and a stencil operational mode, and more particularly,to an improved carbon ribbon lift mechanism embodied therein.

While the quality of the copy produced by carbon ribbon is oftenpreferred over fabric ribbon, one of the disadvantages inherent in theuse of carbon ribbon in a typewriter has been its high rate ofconsumption and the resultant inconvenience occasioned by the frequentneed to replenish the carbon ribbon supply.

As disclosed in Page U.S. Pat. No. 3,349,888, the consumption of carbonribbon and the frequency of replenishing the supply of carbon ribbon ina typewriter may be materially reduced by using half inch carbon ribbon,slightly larger than conventional /l6-inch carbon ribbon, and having thetype contact the /2-inch carbon ribbon in a zigzag" pattern. The zigzagpattern is attained by employing a vibrator mechanism in which thevibrator lifting the ribbon is alternately driven through full andpartial strokes. On the full stroke the ribbon is raised to a maximumelevation so that the type strikes the lower half of the carbon ribbon,while on the partial stroke the ribbon is positioned so that the typestrikes the upper half of the carbon ribbon. After each imprint, whilethe escapement mechanism of the machine advances the carriage so thatthe succeeding imprint is properly spaced from the preceding one, theribbon feed mechanism advances the carriage so that the succeedingimprint is properly spaced from the preceding one, the ribbon feedmechanism advances the ribbon only one-half of a normal escapementspace, resulting in a staggered letter character relation on the ribbon.Thus, with a carbon ribbon only slightly wider than a conventionalribbon, the printing capacity and the lift of a spool of carbon ribbonis substantially doubled. Since the cost of /2-inch ribbon issubstantially the same as the cost of 5/l6-inch ribbon, the economy andconvenience attained by this method of printing is apparent.

While the ribbon-lifting mechanism in the hereinabovementioned Pagepatent for driving a vibrator alternately through full and partialstrokes functions very satisfactorily in a matrix-type machine, it isnot readily adaptable for use in a type bar machine or in a typewriterpossessing the capability of selectively switching between a carbonribbon mode and a fabric ribbon mode by the mere turning ofa selectordial.

SUMMARY In accordance with the present invention a selectively operablecarbon ribbon vibrator assembly is provided in an electric typewriter.The carbon ribbon vibrator assembly includes a vibrator supporting acarbon ribbon and a toggle mechanism connected thereto pivotally mountedon a drive arm. The toggle mechanism is fulcrumed on a bistableshiftable support and operable on each forward stroke of the drive armto open or straighten and on each rearward stroke of the drive arm toclose or break about its fulcrum. A bistable trip lever also pivotallymounted on the drive arm is conditioned on each forward stroke of thedrive arm to shift the position of the fulcrum support on each rearwardstroke of the drive arm whereby the carbon ribbon is elevatedalternately through full and partial strokes on succeeding forwardstrokes of the drive arm.

It is a principal object of the present invention to provide an improvedribbon-lifting mechanism for effecting movement necessary to drive avibrator alternately through full and partial strokes.

Another object of the present invention is to provide an im provedribbon-lifting mechanism for use on a typewriter ofthe type bar type.

Still another object of the present invention is to provide aribbon-lifting mechanism incorporating a positively driven toggle actionfor driving a carbon ribbon vibrator alternately through full andpartial strokes.

Other objects and advantages of the present invention will be apparentfrom the following description, as illustrated in the accompanyingdrawing, which discloses by way of example the principles of theinvention and a preferred embodiment thereof.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. I is a perspective view of a portion of an electric typewriteremploying twin vibrators.

FIG. 2 is a perspective view of a carbon ribbon vibrator elevatingassembly in accordance with the present invention.

FIG. 3 is a perspective view of a manually controlled ribbon selectordial for coupling and uncoupling drive to the carbon ribbon vibratorelevating assembly illustrated in FIG. 2.

FIG. 4, like FIG. 2 is a view showing the carbon ribbon vibratorelevating toggle assembly in a rest position with its fulcrum in itslowermost position and conditioned to elevate and position the upperhalf ofa carbon ribbon shown in FIG. 1 opposite a printing point.

FIG. 5 is a view showing the drive arm in forward motion and the carbonribbon vibrator elevating toggle assembly straightening or opening aboutits fulcrum positioned in its lowermost position and a trip leverpositioned to be conditioned to shift the fulcrum support to positionthe toggle assembly to its uppermost position during the rearwardmovement of the drive arm.

FIG. 6 is a view showing the drive arm at the end of the forward drivestarted in FIG. 5, with the fulcrum of the carbon ribbon vibratorelevating toggle assembly in its lowermost position locating the upperhalf of the carbon ribbon viewed in FIG. 1 opposite the printing point,and the trip lever conditioned to shift the bistable support andposition the fulcrum of the toggle assembly to its uppermost position onthe next rearward stroke.

FIG. 7 is a view showing the drive arm in rearward motion and the carbonribbon vibrator elevating toggle assembly being broken with its fulcrumstill in its lowermost position and the trip lever commencing shiftingof the bistable support to position the fulcrum of the toggle assemblyto its uppermost position.

FIG. 8 is a view showing the drive arm in a rest position at the end ofthe rearward motion started in FIG. 7, with the bistable support shiftedand the fulcrum of the toggle assembly in its uppermost position wherebythe toggle assembly is conditioned to elevate and position the lowerhalf of the carbon ribbon shown in FIG. I opposite the printing point.

FIG. 9 is a view showing the drive arm being driven forward from theFIG. 8 position and the toggle assembly straightening or opening aboutits fulcrum which is still positioned in its uppermost position, and thetrip lever positioned to be conditioned to shift the fulcrum to itslowermost position on the next rearward stroke.

FIG. 10 is a view showing the drive arm at the end of the forward drivestarted in FIG. 9, with the fulcrum of the toggle assembly in itsuppermost position locating the lower half of the carbon ribbon viewedin FIG. 1 opposite the printing point, and the trip lever conditioned toshift the bistable support and position the fulcrum of the toggleassembly to its lowermost position on the next rearward stroke.

FIG. I1 is a view showing the drive arm being driven rearwardly from theFIG. 10 position and the toggle assembly being broken with its fulcrumstill in its uppermost position and the trip lever commencing shiftingof the bistable support to position the fulcrum of the toggle assemblyto its lowermost position at the end of the rearward stroke (FIG. 4).

extend outwardly from the frame carried bracket 64. An overcenter spring69 mounted between the shifting support 62 and the frame bracket 64alternately biases the shifting support plate 62 into contact witheither the upper limit stop 67 of the lower limit stop 68. With the endof the toggle link 59 is pivoted on stud 61 and the shifting plate 62 incontact with the upper limit stop 67, the pivot stud 61 of the toggleassembly 57 is located in its uppermost position and whereby then thetoggle assembly 57 is conditioned to elevate and position the lower halfof the carbon ribbon CR shown in FIG. 1 opposite the printing point ofthe type bar' 28 during the forward stroke of the drive link 47. Withthe shifting plate 62 stud 61 in contact with the lower limit stop 68,the pivot stud 61 of the toggle assembly 57 is in its lowermost positionwhereby during the toggle straightening stroke of the drive link 47 thetoggle assembly 57 will elevate and position the upper half of thecarbon ribbon CR shown in FIG. 1 opposite the printing point of the typebar 28. The opposite shifting of the end of the toggle link 59 pivotedon the stud 61 between the upper limit stop 67 and the lower limit stop68 commences as a result of movement applied to the ends of forwardlyextending upper and lower arms 70 and 71 respectively of the shiftingplate 62 overcoming the bias of the overcenter spring 69.

A generally T-shaped trip lever 72 (as seen in FIG. 4) pivotally mountedat its approximate midpoint on a stud 73 provided on the drive link 47,has a pair of arms 74 and 75 with individual bent-out ears projections76 and 77 at their respective ends, adapted to apply the necessary forceto the end of arm 70 or to the end of arm 71 of the bistable shiftingsupport 62 to overcome the prevalent bias of the overcenter spring 69during the rearward stroke of the drive link 47.

An ear 78, bent out from the drive link 47, is received in an arcuatecutout portion 79 in the trip lever 72 between arms 74 and 75. Thearcuate cutout portion 79 has an upper and a lower shoulder identifiedby numerals 80 and 8I. The trip lever 72 is provided with a central leg82 having an overcenter spring 83 mounted between it and the drive link47 to alternately bias either of the shoulders 80 and 81 into abutmentwith the ear 78. Movement of the shoulders 80 and 81 relative to the ear78 occurs as a result of the force of contact between the trip lever ear77 and a projection 84 extending upwardly from the end ofa lowerforwardly extending arm of the frame bracket 64, or as a result of theforce of contact between the trip lever car 76 and a projection 85extending downwardly from the end of an upper forwardly extending arm ofthe frame bracket 64, when the trip lever 72 through the stud 73 iscarried forward by the drive link 47 as the latter is being actuated.

The correct path of the drive link 47 is assured by a stud stationary 80on to the frame bracket member 64 which extends into a bifurcated slot87 formed in the rear end portion of the drive link 47. Thereby it isassured that the connection of the drive link 47 by its notch 48a withthe stud 49 in the bail arm Ila does not accidentally become disrupted.Rearward, restoring movement of the drive link 47 is limited by a stop88 formed on the frame bracket 64.

In operation when the ribbon selector control wheel 45 is set to acarbon ribbon operational mode of operation as illustrated in FIG. 3,and the carbon ribbon vibrator elevating toggle assembly 57 is in therest position wherein its pivot stud 61 is in its lowermost position asillustrated in FIGS. 2 and 4, the carbon ribbon vibrator elevatingtoggle assembly 57 is conditioned to elevate and position the upper halfof the carbon ribbon CR shown in FIG. 1 opposite the printing pointofthe type bar 28 incident to the next type action.

When such next type action occurs, and the U-bar 11 and its upwardlyextending arm Ila pivot counterclockwise about the cross-shaft, thedrive link 47 moves forward.

As illustrated in FIG. 5, as the drive link 47 moves forward in thedirection of arrow A, from the position in FIG. 4 where it abuts thestop 88, the bent out ear 77 extending from the arm 75 of the trip lever72 strikes the projection 84 extending upwardly from the end of thelower forwardly extending arm of the frame bracket 64, to pivot the triplever 72 counterclockwise until the biasing action of the overcenterspring 83 takes over to complete the started movement so that thus thelower shoulder 81 formed by the arcuate cutout portion 79 in the triplever 72 abuts the bent-out ear 78 on the drive link as illustrated inFIG. 6. Thus the trip lever 72 is now positioned so that subsequentlyduring the restoration of the drive link 47 the bistable shifting plate62 is forcibly moved clockwise so that the toggle assembly 57 assumesthe position seen in FIG.

As the drive link 47 arrives at its forwardmost position shown in FIG. 6with the lower end of the toggle link 59 residing (in its lowermostposition) in contact with the lower limit stop 68, the toggle assembly57 is straightened is pivoting the arm 63 and the vibrator-elevating rod43 clockwise and thus is raising the carbon ribbon vibrator 13 through apartial stroke so as to position the upper half of the carbon ribbonshown in FIG. 1 opposite the printing point of the type bar 28.

After reaching the forwardmost position shown in FIG. 6, the drive link47 restores to the rear by the spring 50, causing the toggle assembly 57to break or to the condition seen in FIG. 8 causing the return of thevibrator-elevating rod 43 and the vibrator 13 to their normal positions.

As viewed in FIG. 7 as the link is restoring to the rear from the FIG. 6to the FIG. 8 position, as shown by arrow B, and since the trip lever 72is conditioned to shift the fulcrum 61 of the toggle assembly 57 to itsuppermost position, (the lower shoulder 81 of the arcuate cut outportion 79 of the trip lever 72 being in abutment with the ear 78), theear 76 extending from the arm 74 of the T-shaped trip lever 72 strikesthe end of arm 70 of the bistable shifting support 62, causing theshifting plate 62 to pivot clockwise about stud 66 until the biasingaction of the overcenter spring 69 takes over and moves the shiftingsupport 62 so that the toggle stud 61 moves to its upper position incontact with the upper limit stop 67 as shown in FIG. 8, thusconditioning the toggle assembly 57 to have capacity to elevate andposition the lower half of the carbon ribbon shown in FIG. I oppositethe printing point of the type bar 28, in response to the next typeaction.

With the next type action operation, the drive link 47 is actuatedforward in the direction of arrow A as shown in FIG. 9 from therearwardmost position illustrated in FIG. 8, in response to the actionof the U-bar ll pivoting counterclockwise about cross shaft 14. Duringthis forward movement of the drive link 47, the ear 76 extending fromthe arm 74 of the trip lever 72 strikes the projection 85 extendingdownwardly from the end of the upper forwardly extending arm of theframe bracket member 64, pivoting the trip lever 72 clockwise until thebiasing action of the overcenter spring 83 takes over so that the uppershoulder of the arcuate cutout portion 79 in the trip lever 72 movesinto abutment with the bent-out stop ear 78 on the drive arm asillustrated in FIG. 10, thus conditioning the trip lever 72 to shift thefulcrum support 62 to position the toggle assembly 57 in its lowermostposition on the next actuating movement of the drive link.

As the drive link 47 becomes actuated to its forwardmost position shownin FIG. I0, with the toggle link 59 anchored on pivot stud 61 (in itsuppermost position) in contact with the upper limit stop 67, the toggleassembly 57 straightens about its joint 60 pivoting the arm 63 and thevibrator elevating rod 43 clockwise through a greater distance thanbefore, thereby raising the vibrator 13 through a full stroke so as toposition the lower half of the carbon ribbon shown in FIG. 1 oppositethe printing point of the type bar 28.

After reaching the forward position shown in FIG. 10, the drive link 47is restored again to the rear (in the direction of arrow B) by thespring 50, causing the toggle assembly 57 to fold about its joint 60 andreturn the vibrator-elevating rod 43 and the vibrator 13 to their normalpositions.

As viewed in FIG. II, the link 47 is being restored rearwardly since thetrip lever 72 during the actuation of the link 47 was conditioned toshift the shift plate and 62 to position the toggle assembly 57 to itslowermost position (the shoulder 80 of the arcuate cutout portion 79 ofthe trip lever 72 being in abutment with the car 78), the ear 77extending from the arm 75 of the trip lever 72 strikes the end of thearm 71 of the shifting plate 62, causing the shifting plate 62 to pivotcounterclockwise about stud 66 until the biasing action of theovercenter spring 69 takes over and moves the shifting plate 62 and thetoggle link 59 anchored on pivot stud 61 to its lower most position incontact with the lower limit stop 68, returning the parts to thepositions shown in FIG. 4 thus conditioning the toggle assembly 57 toelevate and position the upper half of the carbon ribbon CR shown inFIG. I opposite the printing point of type bar 28 in response to thenext type action. The above describes the sequence for two type actionoperations whereby the carbon ribbon is elevated alternately to low andhigh positions and in conjunction with effecting a half letter spaceribbon feed, whereby the type impressions on the ribbon define a zigzagpattern and utilize the optimum ribbon area.

lclaim:

l. A ribbon-lifting mechanism comprising,

a frame,

vibrator-elevating means pivotally supported on said frame,

a ribbon vibrator mounted on said vibrator-elevating means,

a toggle mechanism including a first link having a first end pivotallyjoined to said vibrator-elevating means and a second link having a firstend pivotally connected to a second end of said first link and formingtherewith a toggle linkage,

bistably shiftable support means,

means on said bistably positionable support means carrying said secondlink pivotally at a second end thereof,

drive means connected to said toggle joint, operative in an actuatingstoke to straighten the toggle mechanism and operative in a returnstroke to fold said toggle mechanism,

automatic means operable in response to each return stroke of said drivemeans to shift the position of said bistably shiftable support means,whereby said ribbon vibrator is elevated alternately to one anotherpositions incidental to alternate actuating strokes of said drive means,

said bistably shiftable support means including a pivotally mountedshifting plate movable in one direction from one position to a secondposition and movable in a counterdirection from said second position tosaid first position,

bias means connected to said shifting plate for alternately biasingsaidshifting plate to each of said positions after a partial movementthereto,

said automatic means including a two-armed, pivotally mounted bistabletrip lever on said drive means, said trip lever in one bistable positionon said drive means being capable in return stroke of said drive meansto engage one portion of said pivotally mounted shifting plate to moveit pivotally from said first to said second position and being capablein another bistable position to engage another portion of said shiftingplate to move it pivotally from said second to said first position,

means cooperative between said drive means and said bistable trip leverto provide limits of pivotal movements for said trip lever,

an overcenter spring oppositely connected to said trip lever and saiddrive means for biasing said trip lever bistably to each of said pivotallimits after partial movements thereto,

a frame-supported projection in the path of one of said arms of saidtrip lever effective in successive alternate actuating strokes of saiddrive means to position said trip lever in one of its bistablepositions,

and a frame-supported other projection in the path of the other of saidarms of said trip lever effective in the other actuating strokes of saiddrive means to position said trip lever in its other bistable position.

2. In a machine having a selective typing mechanism operable to effectcharacter imprints at a typing line,

a ribbon vibrator for projecting a ribbon from a retired position toeither one of two positions over a printing line,

an element connected with said vibrator to operate it,

a mechanism responsive to the selective operation and restoration ofsaid typing mechanism to effect respectively an operating and restoringmovement of said element and connected vibrator and comprising,

a normally folded toggle linkage having a first link and a second link,

a pivotal joint between said links,

a pivotal joint connecting said element with said first link at alocation spaced from the pivotal joint which connects it with saidsecond link, 4

a means bistably positionable in one or another position for pivotallysupporting said second toggle link in one or another basic pivotlocation at the link end thereof which is opposite to where it has apivotal joint with said first toggle link,

and means respectively responsive to each selective operation of saidtyping mechanism followed by a restoration thereof, to impartrespectively a straightening movement and a folding movement to saidtoggle,

and means operatively associated with said responsive means to effect inconnection with each consecutive toggle-folding movement a movement ofsaid bistably positionable supporting means from the bistable positionit has occupied to its other bistable position,

said responsive means including a drive link to impart to said togglelinkage in conjunction with each selective operation and restoration ofthe typing mechanism a toggle straightening stroke followed reversely bya togglefolding stroke,

said responsive means including means conditionable in response to eachtoggle-straightening stroke of said drive link, so that said bistablypositionable means in dependency of its then prevalent bistable positionwill in the following toggle-folding stroke of said drive link becomeoperated to the other bistable position.

3. The invention defined in claim 2,

said drive link being pivotally jointed with said toggle linkage so thatsaid drive link in its toggle-straightening stroke moves in thedirection of the straightening action of the toggle linkage to eitherone of two positions dependent on the prevalent basic pivot locationsaid bistably positionable means then affords to the second toggle link,

and a trip means carried on said drive'link and controllable therebyduring the conclusion of its toggle-straightening stroke, due to theposition to which said drive link moves in the direction of thestraightening action of the toggle linkage, to become potent in thetoggle-folding return stroke of said drive link to act on said bistablypositionable means to reverse its bistable position.

4. The invention defined in claim 3,

two frame-supported abutments,

said trip means being a two-armed bistable member pivotally carried onsaid drive link, and the arms of said two-armed member during alternatetoggle straightening strokes of said drive link being adapted to engagealternately one or the other of said abutments to cause opposite rockingmovements of said two-armed bistable member, said two-armed bistablemember, due to being alternately rocked in the toggle straighteningstrokes of said drive link, being effective in the toggle folding returnstrokes to act on said bistably positionable means to reverse itsbistable position.

5. In a machine having a selective typing mechanism operable to effectcharacter imprints at a typing line,

a ribbon vibrator for projecting a ribbon from a retired position toeither one of two positions over a printing line,

an element connected with said vibrator to operate it,

a mechanism responsive to the selective operation and restoration ofsaid typing mechanism to effect respectively an operating and arestoring movement of said element and connected vibrator andcomprising,

a normally folded toggle linkage having a first link and a second link,

a pivotal joint between said links,

a pivotal joint connecting said element with said first link at alocation spaced from the pivotal joint which connects it with saidsecond link,

a means bistably positionable in one or another position for pivotallysupporting said second toggle link in one or another basic pivotlocation at the link end thereof which is opposite to where it has apivotal joint with said first toggle link,

and means respectively responsive to each selective operation andrestoration of said typing mechanism, to impart to said togglerespectively a straightening movement and a folding movement,

and means opcratively associated with said responsive means to effect inconsequence of each consecutive toggle folding movement following atoggle straightening movement, a movement of said bistably positionablesupporting means from the particular bistable position it has occupiedto the other one of its bistable position.

6. The invention defined in claim 5,

said responsive means effecting during the restoration of said typingmechanism each time a forced partial movement of said bistablypositionably means from whichever of said two positions it has occupiedtoward the other position,

and spring means cooperative with said bistably positionable means tocomplete each ofits said started movements.

1. A ribbon-lifting mechanism comprising, a frame, vibrator-elevatingmeans pivotally supported on said frame, a ribbon vibrator mounted onsaid vibrator-eleVating means, a toggle mechanism including a first linkhaving a first end pivotally joined to said vibrator-elevating means anda second link having a first end pivotally connected to a second end ofsaid first link and forming therewith a toggle linkage, bistablyshiftable support means, means on said bistably positionable supportmeans carrying said second link pivotally at a second end thereof, drivemeans connected to said toggle joint, operative in an actuating stroketo straighten the toggle mechanism and operative in a return stroke tofold said toggle mechanism, automatic means operable in response to eachreturn stroke of said drive means to shift the position of said bistablyshiftable support means, whereby said ribbon vibrator is elevatedalternately to one and another positions incidental to alternateactuating strokes of said drive means, said bistably shiftable supportmeans including a pivotally mounted shifting plate movable in onedirection from one position to a second position and movable in acounterdirection from said second position to said first position, biasmeans connected to said shifting plate for alternately biasing saidshifting plate to each of said positions after a partial movementthereto, said automatic means including a two-armed, pivotally mountedbistable trip lever on said drive means, said trip lever in one bistableposition on said drive means being capable in return stroke of saiddrive means to engage one portion of said pivotally mounted shiftingplate to move it pivotally from said first to said second position andbeing capable in another bistable position to engage another portion ofsaid shifting plate to move it pivotally from said second to said firstposition, means cooperative between said drive means and said bistabletrip lever to provide limits of pivotal movements for said trip lever,an overcenter spring oppositely connected to said trip lever and saiddrive means for biasing said trip lever bistably to each of said pivotallimits after partial movements thereto, a frame-supported projection inthe path of one of said arms of said trip lever effective in successivealternate actuating strokes of said drive means to position said triplever in one of its bistable positions, and a frame-supported otherprojection in the path of the other of said arms of said trip levereffective in the other actuating strokes of said drive means to positionsaid trip lever in its other bistable position.
 2. In a machine having aselective typing mechanism operable to effect character imprints at atyping line, a ribbon vibrator for projecting a ribbon from a retiredposition to either one of two positions over a printing line, an elementconnected with said vibrator to operate it, a mechanism responsive tothe selective operation and restoration of said typing mechanism toeffect respectively an operating and a restoring movement of saidelement and connected vibrator and comprising, a normally folded togglelinkage having a first link and a second link, a pivotal joint betweensaid links, a pivotal joint connecting said element with said first linkat a location spaced from the pivotal joint which connects it with saidsecond link, a means bistably positionable in one or another positionfor pivotally supporting said second toggle link in one or another basicpivot location at the link end thereof which is opposite to where it hasa pivotal joint with said first toggle link, and means respectivelyresponsive to each selective operation of said typing mechanism followedby a restoration thereof, to impart respectively a straighteningmovement and a folding movement to said toggle, and means operativelyassociated with said responsive means to effect in connection with eachconsecutive toggle-folding movement a movement of said bistablypositionable supporting means from the bistable position it has occupiedto its other bistable Position, said responsive means including a drivelink to impart to said toggle linkage in conjunction with each selectiveoperation and restoration of the typing mechanism a toggle straighteningstroke followed reversely by a toggle-folding stroke, said responsivemeans including means conditionable in response to eachtoggle-straightening stroke of said drive link, so that said bistablypositionable means in dependency of its then prevalent bistable positionwill in the following toggle-folding stroke of said drive link becomeoperated to the other bistable position.
 3. The invention defined inclaim 2, said drive link being pivotally jointed with said togglelinkage so that said drive link in its toggle-straightening stroke movesin the direction of the straightening action of the toggle linkage toeither one of two positions dependent on the prevalent basic pivotlocation said bistably positionable means then affords to the secondtoggle link, and a trip means carried on said drive link andcontrollable thereby during the conclusion of its toggle-straighteningstroke, due to the position to which said drive link moves in thedirection of the straightening action of the toggle linkage, to becomepotent in the toggle-folding return stroke of said drive link to act onsaid bistably positionable means to reverse its bistable position. 4.The invention defined in claim 3, two frame-supported abutments, saidtrip means being a two-armed bistable member pivotally carried on saiddrive link, and the arms of said two-armed member during alternatetoggle straightening strokes of said drive link being adapted to engagealternately one or the other of said abutments to cause opposite rockingmovements of said two-armed bistable member, said two-armed bistablemember, due to being alternately rocked in the toggle straighteningstrokes of said drive link, being effective in the toggle folding returnstrokes to act on said bistably positionable means to reverse itsbistable position.
 5. In a machine having a selective typing mechanismoperable to effect character imprints at a typing line, a ribbonvibrator for projecting a ribbon from a retired position to either oneof two positions over a printing line, an element connected with saidvibrator to operate it, a mechanism responsive to the selectiveoperation and restoration of said typing mechanism to effectrespectively an operating and a restoring movement of said element andconnected vibrator and comprising, a normally folded toggle linkagehaving a first link and a second link, a pivotal joint between saidlinks, a pivotal joint connecting said element with said first link at alocation spaced from the pivotal joint which connects it with saidsecond link, a means bistably positionable in one or another positionfor pivotally supporting said second toggle link in one or another basicpivot location at the link end thereof which is opposite to where it hasa pivotal joint with said first toggle link, and means respectivelyresponsive to each selective operation and restoration of said typingmechanism, to impart to said toggle respectively a straighteningmovement and a folding movement, and means operatively associated withsaid responsive means to effect in consequence of each consecutivetoggle folding movement following a toggle straightening movement, amovement of said bistably positionable supporting means from theparticular bistable position it has occupied to the other one of itsbistable position.
 6. The invention defined in claim 5, said responsivemeans effecting during the restoration of said typing mechanism eachtime a forced partial movement of said bistably positionable means fromwhichever of said two positions it has occupied toward the otherposition, and spring means cooperative with said bistably positionablemeans to complete each of its said started movements.